The Genealogy of the Jahn Family from Bohemia - Exhibit
Ancestry.com, compiler, "World War I Draft Cards," online (Provo, UT: Ancestry.com, 2002), citing World War I Selective System Draft Registration Cards, 1917-1918, M1509 20,243 rolls. Washington, DC: NARA. Card for Jakob A. Madderom, Chicago Board #21